Underground storm shelters have proven to be effective shelters for tornadoes in many parts of the country. Buried or partially buried storm shelters have been used for many years. The difficulties of incorporating buried storm shelters in residential constructions and neighborhoods include the expense, the lack of space associated with the standard lot, and the presence of shallow bedrock in many areas. The fabrication of traditional storm shelters is also relatively expensive.
The recommended procedure for tornado alerts in many parts of the country is for the residents to move to the center part of their house, such as an interior bathroom or closet. While this strategy is generally effective, there are cases of extremely high winds where residents are not safe in any part of the house and where the only practical effective shelter is one that is below the foundation of the home or buried in the vicinity of the home.
The most common material of construction of existing storm shelters is concrete, which may either be prefabricated in one or more sections for site assembly; or poured in place structures. Although the concrete shelters are strong, there are several disadvantages to that material including difficulty and expense of installation, weight, long-term water resistance, and interior moisture condensation.
An object of the current invention is to provide a storm shelter to be installed below the floor level of a home for use in an emergency. Another object of the invention is to provide a shelter that can be installed without limitations of lot size or easement restrictions.
It is a further object of the present invention to provide a shelter that requires limited excavation.
It is a further object of the present invention to provide such a shelter in a relatively inexpensive prefabricated form.
It is a further object of the present invention to provide a material of construction which is water resistant, which will minimize condensation on the interior of the shelter, and which will provide a shelter that is relatively impervious to water seepage from the outside.
It is a further object of the present invention to provide a shelter with interior surfaces which are smooth, sturdy, corrosion-free, and pleasant.
It is a still further object of the invention to provide an underground emergency shelter system that accomplishes all or some of the above objects in combination.
It is an object of the present invention to provide a prefabricated shelter of a material which is lighter and easier to install than precast concrete. It is a further object of the present invention to provide a shelter which can be built into new construction in a manner which permits entry from the interior of the home. In the current invention it is desirable to place the unit below the floor lever for maximum safety and security.
It is an object of the preferred embodiment of the invention to provide a lightweight underground emergency shelter system and may be anchored by a house foundation without requiring a separate and elaborate anchoring apparatus.
An object of the present invention is to provide a prefabricated shelter which can be constructed with materials such as acrylic which is used in conventional tubs and spas, and which can be fabricated by vendors such as tub and spa vendors. It is a further object of the present invention to provide prefabricated units which can be handled without special equipment such as cranes.
An object of the present invention is to provide a pleasant interior surface in a single unit without requiring an exterior support frame.
One object of the present invention is to provide a smaller and more affordable emergency shelter which does not require elaborate anchoring.
U.S. Pat. No. 4,955,166 for a "Tornado underground shelter" issued on Sep. 11, 1990 to Steve M. Qualline and Louis R. Dunnam describes a large, generally spherical tornado shelter with a seat member is attached to the sidewall and floor which forms a structural member that strengthens the globe. The patent describes disadvantages of concrete structures shrinkage, cracking, and becoming saturated with moisture such that the interior is unsuitable for habitation or storage. The shelter provides standing headroom for its occupants. The '166 patent references a second embodiment of incorporating the large spherical structure into the floor of a home with the entrance above the floor level of the home. The patent also references placing the structure under a patio with the stairway extending at least three steps above the top surface of the patio, thereby precluding someone inadvertently falling through the open door thereof An object of the present invention is to provide a relatively inexpensive prefabricated structure of more practical size that can be incorporated more readily into conventional home designs without increasing the foundation size of home.